Why does nobody seem to think that `null` is a serious problem in D?

[Kagamin]

On Wednesday, 21 November 2018 at 22:24:06 UTC, Johan Engelen 
wrote:
> The issue is not specific to LDC at all. DMD also does 
> optimizations that assume that dereferencing [*] null is UB.

Do you have an example? I think it treats null dereference as 
implementation defined but otherwise safe.